In order for a processing system to communicate to other remote processing systems or devices, the processing system must have an architecture that defines the information flow through the network. One typical network architecture is referred to as Systems Network Architecture (SNA). The Systems Network Architecture comprises a total description of the logical structure, formats, protocols, and operational sequences for transmitting information through the communication system.
Any network architecture is complicated, and involves an extensive group of protocols. Consequently, to establish communications with other systems or devices over a network, an extensive knowledge of the network architecture is needed to ensure the connections meet the protocols of the architecture. A typical system user ordinarily does not have this knowledge base. Thus, a resident expert usually would be needed to assist the everyday user in resolving problems associated with invalid requests.
One solution to resolving these problems was provided in IBM System 38, IBM Displaywriter, and IBM 5280. In these systems a program was provided that prompted the user for desired connections. It then decided whether or not it had received a valid connection from the user. A problem with this solution was that the user did not receive any indication, in the event of an error, of what the user had to do to correct the error. The program did not allow for interaction by the user.
These programs also did not provide the ability to check out contradictions across screens. For example, if a user made one response, that response might limit the available responses on another option screen. These programs did not provide a means to check whether or not the next user response was within the bounds of the available responses, and did not provide cross-checking and interdependency checking.
Also, these programs were not easily adaptable to changes and additions in the protocols of the network architecture. For example, if the protocols of the network architecture were enhanced to provide the ability to add more adapters, modems, and additional communications cards, they did not allow the user to select which applications and adapters the user wanted to support in the network.
Thus, if the network architecture were enhanced to provide additional communications between certain devices, the programs could not support these changes without a costly and burdensome rewrite of the program code.